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Background.Risk factors for Nocardia infection in organ transplant recipients have not been formally assessed in the current era of transplantation. Methods.We performed a matched case-control study (1 : 2 ratio) between January 1995 and December 2005. Control subjects were matched for transplant type and timing. Univariate matched odds ratios were determined and conditional logistic regression was performed to identify independent risk factors. Clinical and microbiological characteristics of all case patients were reviewed. Results.Among 5126 organ transplant recipients, 35 (0.6%) were identified as having cases of Nocardia infection. The highest frequency was among recipients of lung transplants (18 [3.5%] of 521 patients), followed by recipients of heart (10 [2.5%] of 392), intestinal (2 [1.3%] of 155), kidney (3 [0.2%] of 1717), and liver (2 [0.1%] of 1840) transplants. In a comparison of case patients with 70 matched control subjects, receipt of high-dose steroids (odds ratio, 27; 95% confidence interval, 3.2–235; P = .003) and cytomegalovirus disease (odds ratio, 6.9; 95% confidence interval, 1.02–46; P = .047) in the preceding 6 months and a high median calcineurin inhibitor level in the preceding 30 days (odds ratio, 5.8; 95% confidence interval, 1.5–22; P = .012) were found to be independent risk factors for Nocardia infection. The majority of case patients (27 [77%] of 35) had pulmonary disease only. Seven transplant recipients (20%) had disseminated disease. Nocardia nova was the most common species (found in 17 [49%] of the patients), followed by Nocardia farcinica (9 [28%]), Nocardia asteroides (8 [23%]), and Nocardia brasiliensis (1 [3%]). Of the 35 case patients, 24 (69%) were receiving trimethoprim-sulfamethoxazole for Pneumocystis jirovecii pneumonia prophylaxis. Thirty-one case patients (89%) experienced cure of their Nocardia infection. Conclusions.Receipt of high-dose steroids, history of cytomegalovirus disease, and high levels of calcineurin inhibitors are independent risk factors for Nocardia infection in organ transplant recipients. Our study provides insights into the epidemiology of Nocardia infection in the current era, a period in which immunosuppressive and prophylactic regimens have greatly evolved.

Background. Nocardiosis is a rare, life-threatening opportunistic infection, affecting 0.04% to 3.5% of patients after solid organ transplant (SOT). The aim of this study was to identify risk factors for Nocardia infection after SOT and to describe the presentation of nocardiosis in these patients.Methods. We performed a retrospective case-control study of adult patients diagnosed with nocardiosis after SOT between 2000 and 2014 in 36 European (France, Belgium, Switzerland, the Netherlands, Spain) centers. Two control subjects per case were matched by institution, transplant date, and transplanted organ. A multivariable analysis was performed using conditional logistic regression to identify risk factors for nocardiosis.Results. One hundred and seventeen cases of nocardiosis and 234 control patients were included. Nocardiosis occurred at a median of 17.5 (range, 2-244) months after transplant. In multivariable analysis, high calcineurin inhibitor trough levels in the month before diagnosis (odds ratio [OR], 6.11; 95% confidence interval [CI], 2.58-14.51), use of tacrolimus (OR, 2.65; 95% CI, 1.17-6.00) and corticosteroid dose (OR, 1.12; 95% CI, 1.03-1.22) at the time of diagnosis, patient age (OR, 1.04; 95% CI, 1.02-1.07), and length of stay in the intensive care unit after SOT (OR, 1.04; 95% CI, 1.00-1.09) were independently associated with development of nocardiosis; low-dose cotrimoxazole prophylaxis was not found to prevent nocardiosis. Nocardia farcinica was more frequently associated with brain, skin, and subcutaneous tissue infections than were other Nocardia species. Among the 30 cases with central nervous system nocardiosis, 13 (43.3%) had no neurological symptoms.Conclusions. We identified 5 risk factors for nocardiosis after SOT. Low-dose cotrimoxazole was not found to prevent Nocardia infection. These findings may help improve management of transplant recipients.

Nocardiosis caused by Nocardia seriolae is one of the major threats in the aquaculture of Seriola species (yellowtail; S. quinqueradiata, amberjack; S. dumerili and kingfish; S. lalandi) in Japan. Here, we report the complete nucleotide genome sequence of N. seriolae UTF1, isolated from a cultured yellowtail. The genome is a circular chromosome of 8,121,733 bp with a G+C content of 68.1% that encodes 7,697 predicted proteins. In the N. seriolae UTF1 predicted genes, we found orthologs of virulence factors of pathogenic mycobacteria and human clinical Nocardia isolates involved in host cell invasion, modulation of phagocyte function and survival inside the macrophages. The virulence factor candidates provide an essential basis for understanding their pathogenic mechanisms at the molecular level by the fish nocardiosis research community in future studies. We also found many potential antibiotic resistance genes on the N. seriolae UTF1 chromosome. Comparative analysis with the four existing complete genomes, N. farcinica IFM 10152, N. brasiliensis HUJEG-1 and N. cyriacigeorgica GUH-2 and N. nova SH22a, revealed that 2,745 orthologous genes were present in all five Nocardia genomes (core genes) and 1,982 genes were unique to N. seriolae UTF1. In particular, the N. seriolae UTF1 genome contains a greater number of mobile elements and genes of unknown function that comprise the differences in structure and gene content from the other Nocardia genomes. In addition, a lot of the N. seriolae UTF1-specific genes were assigned to the ABC transport system. Because of limited resources in ocean environments, these N. seriolae UTF1 specific ABC transporters might facilitate adaptation strategies essential for marine environment survival. Thus, the availability of the complete N. seriolae UTF1 genome sequence will provide a valuable resource for comparative genomic studies of N. seriolae isolates, as well as provide new insights into the ecological and functional diversity of the genus Nocardia.

Nocardiosis, typically affecting immunocompromised patients, can manifest in rare forms like hand tenosynovitis. We report a 91-year-old man with Nocardia vinacea , confirmed by genetic sequencing after negative cultures, likely caused by a gardening injury. The diagnosis was made early, in less than a week, thanks to molecular biology techniques performed directly on the specimen (synovial biopsy), drastically shortening the time needed to introduce antibiotic therapy adapted to Nocardiosis, as the Nocardia culture grew in around a month. This case emphasizes the need for early PCR testing and tailored diagnostic approaches. Clinical trial NA.

Treatment of actinomycotic mycetoma with joint involvement is challenging. We present a patient in India with actinomycotic mycetoma who reached complete cure and remission after linezolid and meropenem treatment with a 2-year posttreatment follow-up. Clinicians should use novel drug regimens based on subspecies variations of Nocardia and regional drug susceptibility patterns to guide therapy.

Background Nocardia farcinica , a gram-positive filamentous bacterium, is predominantly found in individuals with compromised immune systems. Bacteremia caused by Nocardia farcinica is relatively rare. Case presentation A 58-year-old woman who was diagnosed with systemic lupus erythematosus (SLE) for more than three months presented with a fever that persisted for three days. Following comprehensive diagnostic evaluations, including antinuclear and anti-dsDNA antibody tests, electrocardiogram, lung CT, MRI, and cultures of blood and sputum, the patient was diagnosed with Nocardia farcinica bloodstream infection and disseminated Nocardia disease affecting the intracranial, endocardial, and pulmonary regions. The patient was administered a combination ofsulfamethoxazole‒trimethoprim tablets and linezolid, for anti-infective therapy. Throughout the treatment course, the patient developed symptoms, including headache, chest pain, and back pain, which escalated to sudden confusion, pupil dilation, and ultimately cardiac arrest. Despite resuscitation efforts, the patient died. Conclusion The clinical manifestations and imaging findings of nocardiosis are nonspecific, and diagnosis largely depends on pathogen identification. Clinicians should maintain a high level of suspicion for nocardiosis in immunocompromised patients, particularly those with long-term use of corticosteroids or immunosuppressive agents, and closely monitor the risk of disseminated infection secondary to Nocardia bloodstream infection. Early diagnosis and appropriate use of multiple antibiotics are crucial. In cases of disseminated nocardiosis, especially when critical sites such as the central nervous system or endocardium are involved, a three-drug regimen is recommended to control the infection more effectively and improve patient survival outcomes. Clinical trial The manuscript is a case report; therefore, I declare that a Clinical Trial number is not applicable.

We studied 50 patients with invasive nocardiosis treated during 2004-2023 in intensive care centers in France and Belgium. Most (65%) died in the intensive care unit or in the year after admission. Nocardia infections should be included in the differential diagnoses for patients in the intensive care setting.

To correlate the microbiological and clinical features of infections caused by Nocardia species. We determined the species and drug susceptibility of 138 Nocardia strains isolated from 132 patients at the University of Texas M. D. Anderson Cancer Center (Houston, TX) from 2002 through 2012 and analyzed the clinical features. The 132 patients included 82 men and 50 women with a mean age of 59.1 years. All except two had underlying cancer, and 47 (35.6%) also received a stem cell transplant. These patients experienced 136 episodes of Nocardia infection, including pulmonary infection, abscess of deep skin and soft tissue, bacteremia and dissemination, and brain abscess. The 138 Nocardia strains involved 27 species, of which 20 species have been described since 2000. Common species included Nocardia nova, Nocardia cyriacigeorgica, Nocardia farcinica, and Nocardia abscessus, together accounting for 59.4%. N nova caused most bacteremia cases, whereas N farcinica caused most of the skin and brain infections. Infections with a few recent species likely represented first confirmation or report of human infections. Antimicrobial susceptibility tests of 117 strains showed that they were all susceptible to trimethoprim-sulfamethoxazole and linezolid but variably susceptible to other drugs depending on species. Most patients who were treated for the infection showed improvement or resolution. Diverse Nocardia species can cause secondary infections in patients with cancer. Timely species identification and antimicrobial susceptibility tests may guide treatment.

Background Nocardiosis, despite its rarity and underreporting, is significant due to its severe impact, characterized by high morbidity and mortality rates. The development of a precise, reliable, rapid, and straightforward technique for identifying the pathogenic agent in clinical specimens is crucial to reduce fatality rates and facilitate timely antimicrobial treatment. In this study, we aimed to identify Nocardia spp. in clinical isolates, using MALDI-TOF MS as the primary method, with molecular methods as the gold standard. Clinical Nocardia isolates were identified using 16S rRNA/hsp65/gyrB/secA1/rpoB gene sequencing. Identification performance of the Bruker MALDI Biotyper 3.1 (V09.0.0.0_8468) and MBT Compass 4.1 (V11.0.0.0_10833) for Nocardia identification was evaluated. Results Seventy-six Nocardia isolates were classified into 12 species through gene sequencing. The MALDI Biotyper 3.1 (V09.0.0.0_8468) achieved 100% genus-level accuracy and 84.2% species accuracy (64/76). The MBT Compass 4.1 with the BDAL Database (V11.0.0.0_10833) improved species identification to 98.7% (75/76). The updated database enhanced species level identification with scores > 1.7, increasing from 77.6% (59/76) to 94.7% (72/76), a significant improvement ( P  = 0.001). The new and simplified extraction increased the proportion of strains identified to the species level with scores > 1.7 from 62.0% (18/29) to 86.2% (25/29) ( P  = 0.016). An in-house library construction ensured accurate species identification for all isolates. Conclusions The Bruker mass spectrometer can accurately identify Nocardia species, albeit with some variations observed between different database versions. The MALDI Biotyper 3.1 (V09.0.0.0_8468) has limitations in identifying Nocardia brasiliensis , with some strains only identifiable to the genus level. MBT Compass 4.1 (V11.0.0.0_10833) effectively addresses this shortfall, improving species identification accuracy to 98.7%, and offering quick and reliable identification of Nocardia . Both database versions incorrectly identified the clinically less common Nocardia sputorum as Nocardia araoensis . For laboratories that have not upgraded their databases and are unable to achieve satisfactory identification results for Nocardia, employing the new and simplified extraction method can provide a degree of improvement in identification outcomes.

Micropterus salmoides, adaptable and fast-growing, is a major farmed fish in China. Intensive farming causes multiple diseases, especially hard-to-treat nocardiosis. Vaccines are an effective and safe prevention and control strategy against fish diseases. In this experiment, the highly antigenic HRP1 gene of Nocardia seriolae ( N. seriolae ) was displayed on the surface of Bacillus subtilis ( B. subtilis ), and an oral vaccine (HRP1-cotC- B. subtilis ) was successfully developed. Immune responses in inoculated fish were tested intermittently over 5 weeks post-administration. Immune protection was evaluated via challenge test. Serological parameters testing showed that the activity of lysozyme and Glutathione Peroxidase (GSH-Px) were significantly increased at the 7th and 21st day post-immunization, and the activity of Alkaline Phosphatase was extremely increased compared to the control. q RT-PCR detection found that oral vaccine could significantly boost the IgM expression of spleen and head-kidney. The expression of spleen major histocompatibility complex (MHC) was enhanced, MHCII at the 7th, 21st day and MHCI at 35th day post-immunization respectively. MHCI has an increasing trend in the head-kidney. CD8 increased in both spleen and head-kidney at different stages of immunization. The inflammatory cytokine il-1β and anti-inflammatory cytokine TGF-β significantly increased in head-kidney at 35th day after immunization. The live bacterial vaccine altered the composition of the intestinal flora, demonstrated a decline in Firmicutes and an increase in Fusobacteria, and a significant decrease in Clostridium replaced by Cetobacterium at the genus level. Largemouth bass immunized with HRP1-cotC- B. subtilis spores exhibited a 18.18% relative survival rate after N. seriolae infection. In conclusion, this study developed a novel oral vaccine against N. seriolae in largemouth bass using B. subtilis spore surface display technology. Oral vaccination improves nonspecific immunity, induces innate and cellular immunity, strengthens bacterial resistance, and increases survival after pathogen infection. This offers an effective strategy for controlling fish nocardiosis in aquaculture.